This application is focused on the candidate's immediate career goal, which is to enhance and further his laboratory-based training to date by acquiring new skills in the development, testing and use of globin vectors designed for gene therapy approaches to the beta-chain hemoglobinopathies. With the applicant's clinical background, previous doctoral research experience and three years of post-doctoral work in the laboratory of Dr. Arthur Nienhuis at St. Jude Children's Research Hospital (SJCRH) most recently, the candidate is now entering a transitional phase in his career with the goal of becoming an independent investigator as a clinician-scientist. However, the candidate and the sponsor strongly believe that further training involving the new vectors and animal models outlined in this application will facilitate this transition and greatly enhance the potential for early success as an independent investigator. As an independent faculty member in an academic medical setting, it is the candidate's long-term career goal to continue in the area of gene therapy for hematologic disorders with specific interest in developing a research program compatible with the translation of successful preclinical gene therapy approaches to the clinic. In this application, the candidate proposes to obtain additional training and specific expertise in the development and testing of new therapeutic globin vectors with his current mentor, Dr. Arthur Nienhuis, at SJCRH. Within the Div. of Experimental Hematology in which Dr. Nienhuis is a member and Chief, there is significant expertise in retroviral and lentiviral vector development, in techniques of gene transfer into murine and human hematopoietic stem cells, in animal models of thalassemia, and in the use of the NOD/SCID murine transplant model for human stem cells. Thus, the further training the applicant requires for the execution of the proposed research is readily available. The proposed research project is based on the need for the development of improved globin vectors for use in a gene therapy approach to both thalassemia and sickle cell anemia. The focus of this project involves a gene addition strategy based on the hypothesis that delivery of an optimized gamma-globin gene cassette can achieve a sufficient level of expression in developing erythroid cells to reverse the thalassemic or sickle cell disease phenotype. The project contains 3 specific aims: 1) to design and test novel gamma-globin retroviral and lentiviral vectors, 2) to use a murine model of beta-thalassemia to model gene therapy approaches using optimized gamma-globin vectors. and 3) to characterize and use primitive hematopoietic cells from patients with beta-thalassemia to evaluate the therapeutic potential of optimized gamma-globin vectors.